Some time ago, the animation studios all switched from hand-drawn cartoons and animated films to computer generated images. The reason was cost. Though naturally, the studios also claimed this was what people wanted and that the images looked better. I've never liked the computer drawn images. They feel fake to me, which is an interesting thing to say about a cartoon... which is fake by its very nature.
What bothers me though is the lack of imperfection. When characters were hand drawn, it was virtually impossible to create perfect symmetry, especially when drawing something that was spherical in nature. Thus, the images they drew were all believable and real to me because even though they were animated, they had just enough real world asymmetry to feel natural... as if they could be out there somewhere. But in the computer age, all the drawings are mathematically perfect and all that inescapable asymmetry has vanished. Suddenly, the characters are too perfect to be real, as is nature around them.
That said, there have been two instances lately where I have been able to overlook this and not feel bothered by the glaring symmetry. Interestingly, these exceptions proved the point to me because of what makes them unique. The first is Wreck-It Ralph, and the reason the perfect symmetry in Wreck-It Ralph didn't bother me was because this film takes place in the world of videogames. That means that the characters are meant to have an unreal feel to them. Hence, it was easy to overlook the unreality because you expected the characters to look unreal.
In both instances, the symmetry problem vanished. Few other computer drawn films, however, have similar means of hiding their misguided perfection. That's why I prefer hand-drawn animation, because the imperfection caused by the human hand makes the characters more realistic. It makes them something which can exist in the real world. The perfection which comes with computer drawn images cannot do that. And few animators seem to realize the problem.